This is certainly a positive development. IMO, it should have happened a long time ago, like back in the 1990s, when the first ads hit the Internet. But at least it's happening now.

I have one criticism. The c|net article states that:

Meanwhile, Yahoo won't be sharing information [with ClickForensics] on exactly how its 2,700 filters operate to detect fraud with advertisers because they could then figure out how to circumvent the filters and game the system, Davis says.

Surely, Y! can't think that this information isn't widely known! I imagine ClickForensics either already understands this, or will very shortly. And most certainly, the ever-growing legions of fraudsters know this all too well. Maybe the script kiddies don't yet know it, but it won't take them long to figure it out if they really want to know.

Google still claims that they're capturing the vast majority of the clicks, and that advertisers aren't charged so they don't need to worry, etc. However, this strategy could backfire on Google if their advertisers ROI worsens, and there is no other plausible reason (besides click fraud) for the drop.